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Acetylcholine receptor expression in human extraocular muscles and their susceptibility to myasthenia gravis
Author(s) -
MacLennan C.,
Beeson D.,
Buijs A.M.,
Vincent A.,
NewsomDavis J.
Publication year - 1997
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.410410404
Subject(s) - myasthenia gravis , extraocular muscles , acetylcholine receptor , messenger rna , receptor , endocrinology , medicine , ocular myasthenia , acetylcholine , fetus , muscle weakness , weakness , protein subunit , neuromuscular junction , biology , anatomy , gene , biochemistry , neuroscience , genetics , pregnancy
In myasthenia gravis (MG), extraocular muscle (EOM) weakness is often an initial and persisting symptom. It has been proposed that acetylcholine receptor (AChR) from EOM is antigenically different from AChR of other innervated muscles and that the presence of antibodies to fetal AChR expressed in EOM causes their weakness. We have (1) studied mRNA expression for each of the AChR subunits (α, β, γ, δ, and ϵ) in human muscle, including EOM, and (2) compared the binding of sera from ocular myasthenia gravis (OMG) patients with fetal (α 2 βγδ) and adult (α 2 βϵδ) human AChRs. RNase protection assays showed that expression of the AChR γ‐subunit (fetal‐type) mRNA in EOM was comparable with that in other innervated muscle types. By contrast, ϵ‐subunit (adult‐type) mRNA was expressed at much higher levels in EOM than in other muscles studied. Moreover, some OMG sera bound specifically to adult AChR. These results do not support the contention that susceptibility of EOM in MG results from expression of fetal AChR and indicate that the inclusion of antigen from a source rich in adult AChR in the MG diagnostic assay will increase the yield of positive results in OMG patients.